document_title: Peacock Throne

question_text: name the last mughal emperor to sit on the peacock throne

text: Peacock Throne

text: History[edit]

text: Shah Jahan ruled in what is considered the Golden Age of the vast Mughal Empire, which covered almost all of the Indian subcontinent. It was ruled from the newly constructed capital of Shahjahanabad. The emperor was the focus around which everything else revolved, giving audiences and receiving petitioners. This ruler and his court was to be a mirror image of paradise on earth, in the very centre of the empire; and such a ruler would be worthy of a Throne of Solomon (تخت سليمان, Takht-e-Sulaiman) to underscore his position as a just king. Just like Solomon's throne, the Peacock Throne was to be covered in gold and jewels, with steps leading up to it, with the ruler floating above ground and closer to heaven. Said Gilani and his workmen from the imperial goldsmiths' department were commissioned with the construction of this new throne. It took seven years to complete. Large amounts of solid gold, precious stones and pearls were used, creating a masterful piece of Mughal workmanship that was unsurpassed before or after its creation. It was an opulent indulgence that could only be seen by a small number of courtiers, aristocrats, and visiting dignitaries. The throne was, even by Golden Age Mughal standards, supremely extravagant, costing twice as much as the construction of the Taj Mahal.[1][2][3]

text: The appearance of this new throne was in stark contrast to the older throne of Jahangir, a large rectangular slab of engraved black basalt constructed in the early 1600s, used by the father of Shah Jahan.

text: The new throne was not initially given the name by which it became known. It was simply known as the "Jeweled Throne" or "Ornamented Throne" (Takht-Murassa). It received its name from later historians because of the peacock statues featured on it.[1]

text: The Peacock Throne was inaugurated in a triumphant ceremony on 22 March 1635, the formal seventh anniversary of Shah Jahan's accession.[4] The date was chosen by astrologers and was doubly auspicious, since it coincided exactly with Eid al-Fitr, the end of Ramadan, and Nowruz, the Persian Spring festival. The emperor and the court were returning from Kashmir and it was determined that the third day of Nowruz would be the most auspicious day for him to enter the capital and take his seat on the throne.[5][6]

text: Muhammad Qudsi, the emperor's favourite poet, was chosen to compose twenty verses that were inscribed in emerald and green enamel on the throne. He praised the matchless skill of the artisans, the "heaven-depleting grandeur" of its gold and jewels, and included the date in the letters of the phrase "the throne of the just king".[1][7]

text: Poet Abu-Talib Kalim was given six pieces of gold for each verse in his poem of sixty-three couplets.[8]

text: The master goldsmith Said Gilani was summoned by the emperor and showered with honours, including with his weight in gold coins and given the title "Peerless Master" (Bibadal Khan). Gilani produced a poem of 134 couplets, filled with chronograms, the first twelve couplets giving the date of the emperor's birth, the following thirty-two the date of his first coronation, then ninety couplets giving the date of the throne's inauguration.[8]

text: Towards India he turned his reins quickly and went in all glory,

text:
Driving like the blowing wind, dapple-grey steed swift as lightning.
With bounty and liberality, he returned to the capital;
Round his stirrups were the heavens and angels round his reins.
A thousand thanks! The beauty of the world has revived
With the early glory of the throne of multi-coloured gems.[9]

text: After Shah Jahan's death, his son Aurangzeb, who had the regnal name of Alamgir, ascended the Peacock Throne. Aurangzeb was the last of the strong Mughal emperors. After his death, in 1707, his son Bahadur Shah I reigned from 1707–1712. Bahadur Shah I was able to keep the empire stable, by maintaining a relaxed religious policy; however, after his death the empire was in inexorable decline. A period of political instability, military defeats, and court intrigues led to a succession of weak emperors: Jahandar Shah ruled for one year from 1712–1713, Farrukhsiyar from 1713–1719, Rafi ud-Darajat and Shah Jahan II only for a couple of months in 1719. By the time Muhammad Shah came to power, Mughal power was in serious decline and the empire was vulnerable. Nevertheless, under the generous patronage of Muhammad Shah, the court at Delhi became again a beacon of the arts and culture. Administrative reforms could not however stop the later Mughal-Maratha Wars, which greatly sapped the imperial forces. It was only a question of time until forces from neighbouring Persia saw their chance to invade.

text: Nadir Shah's invasion of India culminated in the Battle of Karnal, on 13 February  1739, and the defeat of Muhammad Shah. Nadir Shah entered Delhi and sacked the city, in the course of which tens of thousands of inhabitants were massacred. Persian troops left Delhi at the beginning of May 1739, taking with them the throne as a war trophy, their haul of treasure amounting to a large reduction in Mughal wealth and an irreplaceable loss of cultural artefacts. Among the known precious stones that Nadir Shah looted were the Akbar Shah, Great Mughal, Great Table, Koh-i-Noor, and Shah diamonds, as well as the Samarian spinel and the Timur ruby. These stones were either part of the Peacock Throne or were in possession of the Mughal emperors. The Akbar Shah Diamond was said to form one of the eyes of a peacock,[10] as did the Koh-i-Noor.[11] The Shah diamond was described by Jean-Baptiste Tavernier as being on the side of the throne.[12] Many of these stones ended up becoming part of the Persian crown jewels or were taken later by the British colonialists.

text: When Nadir Shah was assassinated by his own officers on 19 June 1747, the throne disappeared, most probably being dismantled or destroyed for its valuables, in the ensuing chaos.[13] One of the unsubstantiated rumours claimed the throne was given to the Ottoman Sultan,[14] although this could have been a minor throne produced in Persia and given as a gift. The Persian emperor Fath-Ali Shah commissioned the Sun Throne to be constructed in the early 19th century. The Sun Throne has a platform in the shape of that of the Peacock Throne. Some rumours claim that parts of the original Peacock Throne were used in its construction, although there is no evidence for that. Over time, the Sun Throne was erroneously referred to as the Peacock Throne, a term that was later appropriated by the West as a metonym for the Persian monarchy. No structural parts proven to be of the original Peacock Throne survived. Only some of diamonds and precious stones that are attributed to it have survived and re-worked.

text: A Sikh legend has it that a rectangular stone slab measuring 6 feet (1.8 m) by 4 feet (1.2 m) by 9 inches (230 mm) was uprooted, enchained, and brought by Jassa Singh Ramgarhia to Ramgarhia Bunga, in Amritsar, after the capture of the Red Fort by the combined Dal Khalsa forces of Jassa Singh Ahluwalia and Baghel Singh in 1783, as war booty.[15][16] However, that this stone pedestal does indeed come from the Peacock Throne has not been independently corroborated by scientists and historians.

text: A replacement throne that closely resembled the original was probably constructed for the Mughal emperor, after the Persian invasion.[17] The throne was located on the eastern side of the Divan-i-Khas, towards the windows. This throne however was also lost, possibly during or after the Indian Rebellion of 1857 and the subsequent looting and partial destruction of the Red Fort by the British.[18] The marble pedestal on which it rested has survived and can still be seen today.[19][20]

text: In 1908, the New York Times reported that Caspar Purdon Clarke, Director of the Metropolitan Museum of Art, obtained what was purported to be a marble leg from the pedestal of the throne.[21] Although mentioned in the 1908 annual report, the status of this pedestal leg remains unknown.[19][22][23] There is another marble leg in the Victoria and Albert Museum in London. Where exactly these two pedestal legs originate from, and if they are connected to the Peacock Throne at all, remains unclear.

text: Inspired by the legend of the throne, King Ludwig II of Bavaria installed a romanticised version of it in his Moorish Kiosk in Linderhof Palace, constructed in the 1860s.[citation needed]

text: Descriptions[edit]

text: The contemporary descriptions that are known today of Shah Jahan's throne are from the Mughal historians Abdul Hamid Lahori and Inayat Khan, and the French travellers François Bernier and Jean-Baptiste Tavernier. No known painting that would match their descriptions exists of the throne.

text: By Abdul Hamid Lahori[edit]

text: Abdul Hamid Lahori (d. 1654) describes, in his Padshahnama, the construction of the throne:[24]

text: In the course of years many valuable gems had come into the Imperial jewel-house, each one of which might serve as an ear-drop for Venus, or would adorn the girdle of the Sun. Upon the accession of the Emperor, it occurred to his mind that, in the opinion of far-seeing men, the acquisition of such rare jewels and the keeping of such wonderful brilliants can only render one service, that of adorning the throne of empire. They ought therefore, to be put to such a use, that beholders might share in and benefit by their splendour, and that Majesty might shine with increased brilliancy.

text: It was accordingly ordered that, in addition to the jewels in the Imperial jewel-house, rubies, garnets, diamonds, rich pearls and emeralds, to the value of 200 lacs of rupees, should be brought for the inspection of the Emperor, and that they, with some exquisite jewels of great weight, exceeding 50,000 miskals, and worth eighty-six lacs of rupees, having been carefully selected, should be handed over to Bebadal Khan, the superintendent of the goldsmith's department. There was also to be given to him one lakh of tolas of pure gold, equal to 250,000 miskals in weight and fourteen lakhs of rupees in value.

text: The throne was to be three gaz in length, two and a half in breadth, and five in height, and was to be set with the above-mentioned jewels. The outside of the canopy was to be of enamel work with occasional gems, the inside was to be thickly set with rubies, garnets, and other jewels, and it was to be supported by twelve emerald columns. On the top of each pillar there were to be two peacocks thick set with gems, and between each two peacocks a tree set with rubies and diamonds, emeralds and pearls. The ascent was to consist of three steps set with jewels of fine water.

text: This throne was completed in the course of seven years at a cost of 100 lakhs of rupees. Of the eleven jeweled recesses (takhta) formed around it for cushions, the middle one, intended for the seat of the Emperor, cost ten lakhs of rupees. Among the jewels set in this recess was a ruby worth a lac of rupees, with Shah 'Abbas, the king of Iran, had presented to the late Emperor Jahangir, who sent it to his present Majesty, the Sahib Kiran-i sani, when he accomplished the conquest of the Dakhin.

text: On it were engraved the names of Sahib-kiran (Timur), Mir Shah Rukh, and Mirza Ulugh Beg. When in course of time it came into the possession of Shah 'Abbas, his name was added; and when Jahangir obtained it, he added the name of himself and of his father. Now it received the addition of the name of his most gracious Majesty Shah Jahan. By command of the Emperor, the following masnawi, by Haji Muhammad Jan, the final verse of which contains the date, was placed upon the inside of the canopy in letters of green enamel. . . .

text: On his return to Agra, the Emperor held a court, sat for the first time on his throne.[25]

text: By Inayat Khan[edit]

text: The following is the account given of the throne in the Shahjahannama of Inayat Khan:

text: The Nauroz of the year 1044 fell on the 'Id-i fitr, when His Majesty was to take his seat on the new jeweled throne. This gorgeous structure, with a canopy supported on twelve pillars, measured three yards and a half in length, two and a half in breadth, and five in height, from the flight of steps to the overhanging dome. On his Majesty's accession to the throne, he had commanded that eighty-six lakhs worth of gems and precious stones, and a diamond worth fourteen lakhs, which together make a crore of rupees as money is reckoned in Hindustan, should be used in its decoration. It was completed in seven years, and among the precious stones was a ruby worth a lakh of rupees that Shah 'Abbas Safavi had sent to the late Emperor, on which were inscribed the names of the great Timur Sahih-Kiran, etc.[26]

text: By François Bernier[edit]

text: The French physician and traveller François Bernier described, in his Travels in the Mogul Empire A.D. 1656-1668, the throne in the Diwan-i-Khas:

text: The King appeared seated upon his throne, at the end of the great hall, in the most magnificent attire. His vest was of white and delicately flowered satin, with a silk and gold embroidery of the finest texture. The turban, of gold cloth, had an aigrette whose base was composed of diamonds of an extraordinary size and value, besides an Oriental topaz, which may be pronounced unparalleled, exhibiting a lustre like the sun. A necklace of immense pearls, suspended from his neck, reached to the stomach, in the same manner as many of the Gentiles wear their strings of beads.

text:
The throne was supported by six massive feet, said to be of solid gold, sprinkled over with rubies, emeralds, and diamonds. I cannot tell you with accuracy the number or value of this vast collection of precious stones, because no person may approach sufficiently near to reckon them, or judge of their water and clearness; but I can assure you that there is a confusion of diamonds, as well as other jewels, and that the throne, to the best of my recollection, is valued at four crores of Rupees. I observed elsewhere that a lakh is one hundred thousand[27] rupees, and that a crore is a hundred lakh; so that the throne is estimated at forty millions of rupees, worth sixty millions of pounds [livres] or thereabouts. It was constructed by Shah Jahan, the father of Aurangzeb, for the purpose of displaying the immense quantity of precious stones accumulated successively in the treasury from the spoils of ancient Rajas and Patans, and the annual presents to the Monarch, which every Omrah is bound to make
on certain festivals. The construction and workmanship of the throne are not worthy of the materials; but two
peacocks, covered with jewels and pearls, are well conceived and executed. They were made by a workman of astonishing powers, a Frenchman by birth, named..... who, after defrauding several of the Princes of Europe, by means of false gems, which he fabricated with peculiar skill, sought refuge in the Great Mogul's court, where he made his fortune.

text:
At the foot of the throne were assembled all the Omralis, in splendid apparel, upon a platform surrounded by a silver railing, and covered by a spacious canopy of brocade with deep fringes of gold. The pillars of the hall
were hung with brocades of a gold ground, and flowered satin canopies were raised over the whole expanse of the
extensive apartment fastened with red silken cords, from which were suspended large tassels of silk and gold. The[28] floor was covered entirely with carpets of the richest silk, of immense length and breadth.[29]

text: By Jean-Baptiste Tavernier[edit]

text: The French jeweler Jean-Baptiste Tavernier made his sixth voyage to India between 1663 and 1668. It was his great privilege to be invited to visit the court at Delhi by emperor Aurangzeb himself, where he remained as Aurangzeb's guest for two months, from September 12, 1665 to November 11, 1665.

text: Tavernier was invited so the emperor could inspect the jewels he had brought from the west, with the intent of purchasing them. During this visit, Tavernier not only sold several jewels to the emperor and the emperor's uncle Jafar Khan, but established a close relationship with the emperor that led to a longer stay. Tavernier was invited to stay until the conclusion of the emperor's annual birthday celebrations, during which time he had the opportunity to visit the Red Fort and inspect the Peacock Throne. He was also given the opportunity to inspect the valuable jewels and stones belonging to the emperor, but was not able to see those still kept by Aurangzeb's father Shah Jahan, who was imprisoned at Agra Fort. In January 1666, only few months after Tavernier's stay, Shah Jahan died and Aurangzeb claimed the remaining stones.

text: Tavernier gives a detailed description of the Peacock Throne in his book Les Six Voyages de J. B. Tavernier, which was published in 1676 in two volumes. The account of the throne appears in Chapter VIII of Volume II, in which he describes the preparations for the emperor's annual birthday festival, and also the magnificence of the court. It should be noted that Tavernier is considered among the least reliable from a conventionally historical perspective.[30][31]

text: It should be stated that the Great Mogul has seven magnificent thrones, one wholly covered with diamonds, the others with rubies, emeralds, or pearls.

text: The principal throne, which is placed in the hall of the first court, is nearly of the form and size of our camp-beds; that is to say, it is about 6 feet (1.8 m) long and 4 feet (1.2 m) wide. Upon the four feet, which are very massive and from 20 inches (51 cm) to 25 inches (64 cm) high, are fixed the four bars[32] which support the base of the throne, and upon these bars are ranged twelve columns, which sustain the canopy on three sides, there not being any on that which faces the court. Both the feet and the bars, which are more than 18 inches long, are covered with gold inlaid and enriched with numerous diamonds, rubies, and emeralds.

text: In the middle of each bar there is a large balass ruby, cut en cabuchon, with four emeralds round it, which form a square cross. Next in succession, from one side to the other along the length of the bars there are similar crosses, arranged so that in one the ruby is in the middle of four emeralds, and in another the emerald is in the middle and four balass rubies surround it. The emeralds are table-cut, and the intervals between the rubies and emeralds are covered with diamonds, the largest of which do not exceed 10 to 12 carats in weight, all being showy stones, but very flat.

text: There are also in some parts pearls set in gold, and upon one of the longer sides of the throne there are four steps to ascend it. Of the three cushions or pillows which are upon the throne, that which is placed behind the King's back is large and round like one of our bolsters, and the two others that are placed at his sides are flat. There is to be seen, moreover, a sword suspended from this throne, a mace, a round shield, a bow and quiver with arrows; and all these weapons, as also the cushion and steps, both of this throne and the other six, are covered over with stones which match those with which each of the thrones is respectively enriched.

text: I counted the large balass rubies on the great throne, and there are about 108, all cabuchons, the least of which weighs 100 carats, but there are some which weigh apparently 200 and more. As for the emeralds, there are plenty of good colour, but they have many flaws; the largest may weigh 60 carats and the least 30 carats. I counted about 116; thus there are more emeralds than rubies.

text: The underside of the canopy is covered with diamonds and pearls, with a fringe of pearls all round, and above the canopy, which is a quadrangular-shaped dome, there is to be seen a peacock with elevated tail made of blue sapphires and other coloured stones, the body being of gold inlaid with precious stones, having a large ruby in front of the breast, from whence hangs a pear-shaped pearl of 50 carats or thereabouts, and of a somewhat yellow water. On both sides of[33] the peacock there is a large bouquet of the same height as the bird, and consisting of many kinds of flowers made of gold inlaid with precious stones. On the side of the throne which is opposite the court there is to be seen a jewel consisting of a diamond of from 80 to 90 carats weight, with rubies and emeralds round it, and when the King is seated he has this jewel in full view.

text: But that which in my opinion is the most costly thing about this magnificent throne is, that the twelve columns supporting the canopy are surrounded with beautiful rows of pearls, which are round and of fine water, and weigh from 6 to 10 carats each. At 4 feet distance from the throne there are fixed, on either side, two umbrellas, the sticks of which for 7 or 8 feet in height are covered with diamonds, rubies, and pearls. The umbrellas are of red velvet, and are embroidered and fringed all round with pearls.

text: This is what I have been able to observe regarding this famous throne, commenced by Tamerlane and completed by Shāhjahān; and those who keep the accounts of the King’s jewels, and of the cost of this great work, have assured me that it amounts to 107,000 lakhs of rupees, which amount to 160,500,000 livres of our money.[34]

text: Tavernier, however, describes seeing the throne in what is probably the Diwan-i-Am. One theory is that the throne was sometimes moved between the two halls, depending on the occasion. Tavernier also describes five other thrones in the Diwan-i-Khas.

text: Discrepancies between descriptions of Lahori and Tavernier[edit]

text: The descriptions of Lahori, from before 1648, and Tavernier's, published in 1676, are generally in broad agreement on the most important features of the thrones, such as its rectangular shape, standing on four legs at its corners, the 12 columns on which the canopy rests, and the type of gemstones embedded on the throne, such as balas rubies, emeralds, pearls, diamonds, and other coloured stones. There are however some significant differences between the two descriptions:

text:
Lahori's account of the throne, based on the language used, could be a description of the projected design. Tavernier's account of the throne seems to be an eye-witness observation during his visit, in 1665, to the Red Fort. It could be that there were differences between the projected and final designs of the throne that Shah Jahān ascended for the first time on March 12, 1635.
According to Lahori, the throne was to have a length of 3 yards (9 feet) and a breadth of 2½ yards (7½ feet). Tavernier however gives the length at 6 feet and breadth of 4 feet. The height is described by Lahori as 5 yards (15 feet), but Tavernier's account does not mention its total height. Only the height of the four legs at the corners are mentioned, which was about 2 feet.
Lahori describes the canopy as being supported by 12 emerald columns, Tavernier describes 12 columns that were surrounded by and embedded with rows of pearls, which were round and of fine water, and which weighed from 6 to 10 carats each. He thinks these pearls were in fact the most costly and precious aspect of the throne.
A major difference is the position of the eponymous peacock statues. Lahori states that on the top of each pillar there were to be two peacocks, thick-set with gems, and between each two peacocks, a tree set with rubies and diamonds, emeralds and pearls. If the reference to "pillar" here means "column" there would be 24 peacocks right round the throne. Tavernier however saw only a single large peacock above the quadrangular-shaped, dome-like canopy, with an elevated tail, embedded with blue sapphires and other coloured stones, the body of the peacock being made of gold inlaid with precious stones, having a large ruby in front of the breast, from which hung a pear-shaped pearl around 60 carats in weight. Apart from the single large peacock, Tavernier's account speaks of a large bouquet, representing many kinds of flowers, made of gold inlaid with precious stones, of the same height as the peacock, situated on either side of the peacock.
According to Lahori, ascending the throne was by way of three steps, which were also set with jewels of fine water. Tavernier however describes four steps on the longer side of the throne and embedded with the same types of gemstones used on the throne, and with matching designs.

text: Apart from the significant differences between the two accounts given above, there are several details given in Lahori's account that are not mentioned in Tavernier's, and vice versa.

text: Lahori's description[edit]

text:
Lahori's account mentions several historical diamonds that decorated the throne, such as the 186-carat Koh-i-Noor diamond, the 95-carat Akbar Shah diamond, the 88.77-carat Shah diamond and the 83-carat Jahangir diamond, apart from the 352.50-carat Timur Ruby, the third-largest balas ruby in the world. Tavernier makes no mention of these most precious stones. One explanation is that when Tavernier saw the throne in 1665, all these historical diamonds and the balas ruby were in the possession of Shah Jahan, who was under house arrest at the Fort in Agra. Shah Jahan died on 22 January 1666—two months after Tavernier left Delhi, and reached Bengal, during this, his sixth, and last, voyage to India—and his son and successor Aurangzeb was able to claim all these gems. Lahori's descriptions were made during the rule of Shah Jahan, when all the gems were probably incorporated in the throne.
According to Lahori, a twenty-couplet poem by the poet Muhammad Qudsi praising Shah Jahan in emerald letters was embedded in the throne. Tavernier does not mention this in his account, either because of his inability to read and understand what was written, or because Aurangzeb had ordered its removal.

text: Tavernier's description[edit]

text: Tavernier was allowed to closely inspect the throne and its jewels and wrote the most well known detailed description to date.

text:
In his account, Tavernier gave details of the design in which the balas rubies, emeralds, diamonds, and pearls were arranged on the four horizontal bars connecting the four vertical legs, from which the 12 vertical columns, supporting the canopy, arose. In the middle of each bar, a large cabochon-cut balas ruby was placed, surrounded by four emeralds forming a square cross. Smaller such square crosses were situated on either side of the central large cross, along the length of the bar, but arranged in such a way that while in one square cross a balas ruby occupied the center, surrounded by four emeralds, in the next square cross, an emerald was surrounded by four balas rubies. The emeralds were table-cut and the intervals between the emerald-and-ruby crosses, were covered with diamonds, also table-cut and not exceeding 10 to 12 carats in weight.
There were three cushions or pillows upon the throne. The one placed behind the emperor's back was large and round; the other two, placed at his sides, were flat. The cushions were also studded with gems.
Tavernier mentioned some royal standards and weapons that were suspended from the throne, such as a mace, a sword and a round shield, and a bow and quiver with arrows, all studded with gemstones.
He counted the number of large balas rubies and emeralds on the throne. Accordingly, there were 108 large balas rubies on the throne, all cabochon-cut, the smallest weighing around 100 carats and the largest over 200 carats in weight. He counted 116 large emeralds on the throne, all of excellent colour, but with many flaws (a characteristic feature of emeralds), the smallest weighing around 30 carats and the largest around 60 carats.
The underside of the canopy was covered with diamonds and pearls, with a fringe of pearls all round.
On the side of the throne facing the court was suspended a diamond of 80 to 90 carats in weight, with rubies and emeralds surrounding it. When the Emperor was seated on the throne, this suspended arrangement of jewels was in full view in front of him.
Tavernier then wrote about two large gem-studded royal umbrellas, which were not part of the throne, but were placed on either side of the throne, at a distance of 4 feet from it. The central stems of these umbrellas, 7 to 8 feet long, were covered with diamonds, rubies, and pearls. The cloth of the umbrella was made of red velvet, and embroidered and fringed all round with pearls. The height of these umbrellas might give an indication as to the height of the throne, which was probably of the same height. Thus, the height of the throne would have been around 7 to 10 feet.

text: Later Peacock Throne[edit]

text: After Nader Shah looted the original, another throne was made for the Mughal emperor. Along with the Peacock Throne, Nader had also taken the fabulous Koh-i Noor and Darya-i Noor diamonds to Persia, where some became part of the Persian crown jewels, and others were sold to the Ottomans. The plunder taken by Nader was so great that he stopped taxation for 3 years. The bottom half of the Peacock Throne might have been converted into the Sun Throne also a part of the Persian crown jewels. Various 19th-century Indian paintings of this later throne exist. It was located in the Diwan-i-Khas and might have been smaller in size than the original. However, the appearance would have been similar, based on either the original plans or from memory and eye-witness accounts. The replacement throne was made out of gold, or was gilded, and was studded with precious and semi-precious stones. Just like the original, it featured 12 columns. The columns carried a Bengali do-chala roof, which was graced with two peacock statues on the two ends, carrying pearl necklaces in their beaks, and two peacocks at the top, also carrying pearl necklaces in their beaks. The two lower peacocks were in the center underneath a flower bouquet made out of jewels, or under a royal umbrella. This throne was protected by a canopy made out of precious and colorful textiles, and gold and silver threads. The canopy was carried by four slender columns or beams made out of metal. Underneath the throne, colorful and precious carpets were laid out.


document_title: Oxygen

question_text: oxygen (o2) is formed in photosynthesis as a direct result of

question_tokens: oxygen ( o2 ) is formed in photosynthesis as a direct result of

root

text: Oxygen

text: History

text: Early experiments

text: One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck.[3] Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration.[4]

tag: p

text: In the late 17th century, Robert Boyle proved that air is necessary for combustion. English chemist John Mayow (1641–1679) refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus.[5] In one experiment, he found that placing either a mouse or a lit candle in a closed container over water caused the water to rise and replace one-fourteenth of the air's volume before extinguishing the subjects.[6] From this he surmised that nitroaereus is consumed in both respiration and combustion.

text: Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it.[5] He also thought that the lungs separate nitroaereus from air and pass it into the blood and that animal heat and muscle movement result from the reaction of nitroaereus with certain substances in the body.[5] Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract "De respiratione".[6]

text: Phlogiston theory

text: Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element.[7] This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes.[8]

text: Established in 1667 by the German alchemist J. J. Becher, and modified by the chemist Georg Ernst Stahl by 1731,[9] phlogiston theory stated that all combustible materials were made of two parts. One part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx.[4]

text: Highly combustible materials that leave little residue, such as wood or coal, were thought to be made mostly of phlogiston; non-combustible substances that corrode, such as iron, contained very little. Air did not play a role in phlogiston theory, nor were any initial quantitative experiments conducted to test the idea; instead, it was based on observations of what happens when something burns, that most common objects appear to become lighter and seem to lose something in the process.[4]

text: Discovery

text: Oxygen was first discovered by Swedish pharmacist Carl Wilhelm Scheele. He had produced oxygen gas by heating mercuric oxide and various nitrates in 1771–2.[10][11][4] Scheele called the gas "fire air" because it was the only known supporter of combustion, and wrote an account of this discovery in a manuscript he titled Treatise on Air and Fire, which he sent to his publisher in 1775. That document was published in 1777.[12]

text: In the meantime, on August 1, 1774, an experiment conducted by the British clergyman Joseph Priestley focused sunlight on mercuric oxide (HgO) inside a glass tube, which liberated a gas he named "dephlogisticated air".[11] He noted that candles burned brighter in the gas and that a mouse was more active and lived longer while breathing it. After breathing the gas himself, he wrote: "The feeling of it to my lungs was not sensibly different from that of common air, but I fancied that my breast felt peculiarly light and easy for some time afterwards."[7] Priestley published his findings in 1775 in a paper titled "An Account of Further Discoveries in Air" which was included in the second volume of his book titled Experiments and Observations on Different Kinds of Air.[4][13] Because he published his findings first, Priestley is usually given priority in the discovery.

text: The French chemist Antoine Laurent Lavoisier later claimed to have discovered the new substance independently. Priestley visited Lavoisier in October 1774 and told him about his experiment and how he liberated the new gas. Scheele also posted a letter to Lavoisier on September 30, 1774 that described his discovery of the previously unknown substance, but Lavoisier never acknowledged receiving it (a copy of the letter was found in Scheele's belongings after his death).[12]

text: Lavoisier's contribution

text: Lavoisier conducted the first adequate quantitative experiments on oxidation and gave the first correct explanation of how combustion works.[11] He used these and similar experiments, all started in 1774, to discredit the phlogiston theory and to prove that the substance discovered by Priestley and Scheele was a chemical element.

text: In one experiment, Lavoisier observed that there was no overall increase in weight when tin and air were heated in a closed container.[11] He noted that air rushed in when he opened the container, which indicated that part of the trapped air had been consumed. He also noted that the tin had increased in weight and that increase was the same as the weight of the air that rushed back in. This and other experiments on combustion were documented in his book Sur la combustion en général, which was published in 1777.[11] In that work, he proved that air is a mixture of two gases; 'vital air', which is essential to combustion and respiration, and azote (Gk. ἄζωτον "lifeless"), which did not support either. Azote later became nitrogen in English, although it has kept the earlier name in French and several other European languages.[11]

text: Lavoisier renamed 'vital air' to oxygène in 1777 from the Greek roots ὀξύς (oxys) (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), because he mistakenly believed that oxygen was a constituent of all acids.[14] Chemists (such as Sir Humphry Davy in 1812) eventually determined that Lavoisier was wrong in this regard (hydrogen forms the basis for acid chemistry), but by then the name was too well established.[15]

text: Oxygen entered the English language despite opposition by English scientists and the fact that the Englishman Priestley had first isolated the gas and written about it. This is partly due to a poem praising the gas titled "Oxygen" in the popular book The Botanic Garden (1791) by Erasmus Darwin, grandfather of Charles Darwin.[12]

text: Later history

text: John Dalton's original atomic hypothesis presumed that all elements were monatomic and that the atoms in compounds would normally have the simplest atomic ratios with respect to one another. For example, Dalton assumed that water's formula was HO, giving the atomic mass of oxygen was 8 times that of hydrogen, instead of the modern value of about 16.[16] In 1805, Joseph Louis Gay-Lussac and Alexander von Humboldt showed that water is formed of two volumes of hydrogen and one volume of oxygen; and by 1811 Amedeo Avogadro had arrived at the correct interpretation of water's composition, based on what is now called Avogadro's law and the diatomic elemental molecules in those gases.[17][a]

text: By the late 19th century scientists realized that air could be liquefied and its components isolated by compressing and cooling it. Using a cascade method, Swiss chemist and physicist Raoul Pierre Pictet evaporated liquid sulfur dioxide in order to liquefy carbon dioxide, which in turn was evaporated to cool oxygen gas enough to liquefy it. He sent a telegram on December 22, 1877 to the French Academy of Sciences in Paris announcing his discovery of liquid oxygen.[18] Just two days later, French physicist Louis Paul Cailletet announced his own method of liquefying molecular oxygen.[18] Only a few drops of the liquid were produced in each case and no meaningful analysis could be conducted. Oxygen was liquified in a stable state for the first time on March 29, 1883 by Polish scientists from Jagiellonian University, Zygmunt Wróblewski and Karol Olszewski.[19]

text:
In 1891 Scottish chemist James Dewar was able to produce enough liquid oxygen for study.[20] The first commercially viable process for producing liquid oxygen was independently developed in 1895 by German engineer Carl von Linde and British engineer William Hampson. Both men lowered the temperature of air until it liquefied and then distilled the component gases by boiling them off one at a time and capturing them separately.[21] Later, in 1901, oxyacetylene welding was demonstrated for the first time by burning a mixture of acetylene and compressed O
2. This method of welding and cutting metal later became common.[21]

text: In 1923, the American scientist Robert H. Goddard became the first person to develop a rocket engine that burned liquid fuel; the engine used gasoline for fuel and liquid oxygen as the oxidizer. Goddard successfully flew a small liquid-fueled rocket 56 m at 97 km/h on March 16, 1926 in Auburn, Massachusetts, US.[21][22]

text: Oxygen levels in the atmosphere are trending slightly downward globally, possibly because of fossil-fuel burning.[23]

text: Characteristics

text: Properties and molecular structure

text:
At standard temperature and pressure, oxygen is a colorless, odorless, and tasteless gas with the molecular formula O
2, referred to as dioxygen.[25]

text: As dioxygen, two oxygen atoms are chemically bound to each other. The bond can be variously described based on level of theory, but is reasonably and simply described as a covalent double bond that results from the filling of molecular orbitals formed from the atomic orbitals of the individual oxygen atoms, the filling of which results in a bond order of two. More specifically, the double bond is the result of sequential, low-to-high energy, or Aufbau, filling of orbitals, and the resulting cancellation of contributions from the 2s electrons, after sequential filling of the low σ and σ* orbitals; σ overlap of the two atomic 2p orbitals that lie along the O-O molecular axis and π overlap of two pairs of atomic 2p orbitals perpendicular to the O-O molecular axis, and then cancellation of contributions from the remaining two of the six 2p electrons after their partial filling of the lowest π and π* orbitals.[24]

text:
This combination of cancellations and σ and π overlaps results in dioxygen's double bond character and reactivity, and a triplet electronic ground state. An electron configuration with two unpaired electrons, as is found in dioxygen orbitals (see the filled π* orbitals in the diagram) that are of equal energy—i.e., degenerate—is a configuration termed a spin triplet state. Hence, the ground state of the O
2 molecule is referred to as triplet oxygen.[26][b] The highest energy, partially filled orbitals are antibonding, and so their filling weakens the bond order from three to two. Because of its unpaired electrons, triplet oxygen reacts only slowly with most organic molecules, which have paired electron spins; this prevents spontaneous combustion.[27]

text:
In the triplet form, O
2 molecules are paramagnetic. That is, they impart magnetic character to oxygen when it is in the presence of a magnetic field, because of the spin magnetic moments of the unpaired electrons in the molecule, and the negative exchange energy between neighboring O
2 molecules.[20] Liquid oxygen is so magnetic that, in laboratory demonstrations, a bridge of liquid oxygen may be supported against its own weight between the poles of a powerful magnet.[28][c]

text:
Singlet oxygen is a name given to several higher-energy species of molecular O
2 in which all the electron spins are paired. It is much more reactive with common organic molecules than is molecular oxygen per se. In nature, singlet oxygen is commonly formed from water during photosynthesis, using the energy of sunlight.[29] It is also produced in the troposphere by the photolysis of ozone by light of short wavelength,[30] and by the immune system as a source of active oxygen.[31] Carotenoids in photosynthetic organisms (and possibly animals) play a major role in absorbing energy from singlet oxygen and converting it to the unexcited ground state before it can cause harm to tissues.[32]

text: Allotropes

text:
The common allotrope of elemental oxygen on Earth is called dioxygen, O
2, the major part of the Earth's atmospheric oxygen (see Occurrence). O2 has a bond length of 121 pm and a bond energy of 498 kJ·mol−1,[33] which is smaller than the energy of other double bonds or pairs of single bonds in the biosphere and responsible for the exothermic reaction of O2 with any organic molecule.[27][34] Due to its energy content, O2 is used by complex forms of life, such as animals, in cellular respiration. Other aspects of O
2 are covered in the remainder of this article.

text:
Trioxygen (O
3) is usually known as ozone and is a very reactive allotrope of oxygen that is damaging to lung tissue.[35] Ozone is produced in the upper atmosphere when O
2 combines with atomic oxygen made by the splitting of O
2 by ultraviolet (UV) radiation.[14] Since ozone absorbs strongly in the UV region of the spectrum, the ozone layer of the upper atmosphere functions as a protective radiation shield for the planet.[14] Near the Earth's surface, it is a pollutant formed as a by-product of automobile exhaust.[35] At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft.[36]

text:
The metastable molecule tetraoxygen (O
4) was discovered in 2001,[37][38] and was assumed to exist in one of the six phases of solid oxygen. It was proven in 2006 that this phase, created by pressurizing O
2 to 20 GPa, is in fact a rhombohedral O
8 cluster.[39] This cluster has the potential to be a much more powerful oxidizer than either O
2 or O
3 and may therefore be used in rocket fuel.[37][38] A metallic phase was discovered in 1990 when solid oxygen is subjected to a pressure of above 96 GPa[40] and it was shown in 1998 that at very low temperatures, this phase becomes superconducting.[41]

text: Physical properties

text:
Oxygen dissolves more readily in water than nitrogen, and in freshwater more readily than seawater. Water in equilibrium with air contains approximately 1 molecule of dissolved O
2 for every 2 molecules of N
2 (1:2), compared with an atmospheric ratio of approximately 1:4. The solubility of oxygen in water is temperature-dependent, and about twice as much (14.6 mg·L−1) dissolves at 0 °C than at 20 °C (7.6 mg·L−1).[7][42] At 25 °C and 1 standard atmosphere (101.3 kPa) of air, freshwater contains about 6.04 milliliters (mL) of oxygen per liter, and seawater contains about 4.95 mL per liter.[43] At 5 °C the solubility increases to 9.0 mL (50% more than at 25 °C) per liter for water and 7.2 mL (45% more) per liter for sea water.

text:
Oxygen gas dissolved in water at sea-level

5 °C
25 °C

Freshwater
9.0 mL
6.04 mL

Seawater
7.2 mL
4.95 mL

tag: table

text:
Oxygen condenses at 90.20 K (−182.95 °C, −297.31 °F), and freezes at 54.36 K (−218.79 °C, −361.82 °F).[44] Both liquid and solid O
2 are clear substances with a light sky-blue color caused by absorption in the red (in contrast with the blue color of the sky, which is due to Rayleigh scattering of blue light). High-purity liquid O
2 is usually obtained by the fractional distillation of liquefied air.[45] Liquid oxygen may also be condensed from air using liquid nitrogen as a coolant.[46]

text: Oxygen is a highly reactive substance and must be segregated from combustible materials.[46]

text: The spectroscopy of molecular oxygen is associated with the atmospheric processes of aurora and airglow.[47] The absorption in the Herzberg continuum and Schumann–Runge bands in the ultraviolet produces atomic oxygen that is important in the chemistry of the middle atmosphere.[48] Excited state singlet molecular oxygen is responsible for red chemiluminescence in solution.[49]

text: Isotopes and stellar origin

text: Naturally occurring oxygen is composed of three stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant (99.762% natural abundance).[50]

text: Most 16O is synthesized at the end of the helium fusion process in massive stars but some is made in the neon burning process.[51] 17O is primarily made by the burning of hydrogen into helium during the CNO cycle, making it a common isotope in the hydrogen burning zones of stars.[51] Most 18O is produced when 14N (made abundant from CNO burning) captures a 4He nucleus, making 18O common in the helium-rich zones of evolved, massive stars.[51]

text: Fourteen radioisotopes have been characterized. The most stable are 15O with a half-life of 122.24 seconds and 14O with a half-life of 70.606 seconds.[50] All of the remaining radioactive isotopes have half-lives that are less than 27 s and the majority of these have half-lives that are less than 83 milliseconds.[50] The most common decay mode of the isotopes lighter than 16O is β+ decay[52][53][54] to yield nitrogen, and the most common mode for the isotopes heavier than 18O is beta decay to yield fluorine.[50]

text: Occurrence

text:
Ten most common elements in the Milky Way Galaxy estimated spectroscopically[55]

Z
Element
Mass fraction in parts per million

1
Hydrogen
739,000
71 × mass of oxygen (red bar)

2
Helium
240,000
23 × mass of oxygen (red bar)

8
Oxygen
10,400
10400

6
Carbon
4,600
4600

10
Neon
1,340
1340

26
Iron
1,090
1090

7
Nitrogen
960
960

14
Silicon
650
650

12
Magnesium
580
580

16
Sulfur
440
440

text:
Oxygen is the most abundant chemical element by mass in the Earth's biosphere, air, sea and land. Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium.[56] About 0.9% of the Sun's mass is oxygen.[11] Oxygen constitutes 49.2% of the Earth's crust by mass[57] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust. It is also the major component of the world's oceans (88.8% by mass).[11] Oxygen gas is the second most common component of the Earth's atmosphere, taking up 20.8% of its volume and 23.1% of its mass (some 1015 tonnes).[11][58][d] Earth is unusual among the planets of the Solar System in having such a high concentration of oxygen gas in its atmosphere: Mars (with 0.1% O
2 by volume) and Venus have much less. The O
2 surrounding those planets is produced solely by the action of ultraviolet radiation on oxygen-containing molecules such as carbon dioxide.

text: The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. This biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration, decay, and combustion remove it from the atmosphere. In the present equilibrium, production and consumption occur at the same rate.[59]

text:
Free oxygen also occurs in solution in the world's water bodies. The increased solubility of O
2 at lower temperatures (see Physical properties) has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content.[60] Water polluted with plant nutrients such as nitrates or phosphates may stimulate growth of algae by a process called eutrophication and the decay of these organisms and other biomaterials may reduce the O
2 content in eutrophic water bodies. Scientists assess this aspect of water quality by measuring the water's biochemical oxygen demand, or the amount of O
2 needed to restore it to a normal concentration.[61]

text: Analysis

text: Paleoclimatologists measure the ratio of oxygen-18 and oxygen-16 in the shells and skeletons of marine organisms to determine the climate millions of years ago (see oxygen isotope ratio cycle). Seawater molecules that contain the lighter isotope, oxygen-16, evaporate at a slightly faster rate than water molecules containing the 12% heavier oxygen-18, and this disparity increases at lower temperatures.[62] During periods of lower global temperatures, snow and rain from that evaporated water tends to be higher in oxygen-16, and the seawater left behind tends to be higher in oxygen-18. Marine organisms then incorporate more oxygen-18 into their skeletons and shells than they would in a warmer climate.[62] Paleoclimatologists also directly measure this ratio in the water molecules of ice core samples as old as hundreds of thousands of years.

text: Planetary geologists have measured the relative quantities of oxygen isotopes in samples from the Earth, the Moon, Mars, and meteorites, but were long unable to obtain reference values for the isotope ratios in the Sun, believed to be the same as those of the primordial solar nebula. Analysis of a silicon wafer exposed to the solar wind in space and returned by the crashed Genesis spacecraft has shown that the Sun has a higher proportion of oxygen-16 than does the Earth. The measurement implies that an unknown process depleted oxygen-16 from the Sun's disk of protoplanetary material prior to the coalescence of dust grains that formed the Earth.[63]

text: Oxygen presents two spectrophotometric absorption bands peaking at the wavelengths 687 and 760 nm. Some remote sensing scientists have proposed using the measurement of the radiance coming from vegetation canopies in those bands to characterize plant health status from a satellite platform.[64] This approach exploits the fact that in those bands it is possible to discriminate the vegetation's reflectance from its fluorescence, which is much weaker. The measurement is technically difficult owing to the low signal-to-noise ratio and the physical structure of vegetation; but it has been proposed as a possible method of monitoring the carbon cycle from satellites on a global scale.

text: Biological role of O2

text: Photosynthesis and respiration

text: In nature, free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. According to some estimates, green algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on Earth, and the rest is produced by terrestrial plants.[65] Other estimates of the oceanic contribution to atmospheric oxygen are higher, while some estimates are lower, suggesting oceans produce ~45% of Earth's atmospheric oxygen each year.[66]

text: A simplified overall formula for photosynthesis is:[67]

text: or simply

text:
Photolytic oxygen evolution occurs in the thylakoid membranes of photosynthetic organisms and requires the energy of four photons.[e] Many steps are involved, but the result is the formation of a proton gradient across the thylakoid membrane, which is used to synthesize adenosine triphosphate (ATP) via photophosphorylation.[68] The O
2 remaining (after production of the water molecule) is released into the atmosphere.[f]

text: Oxygen is used in mitochondria to generate ATP during oxidative phosphorylation. The reaction for aerobic respiration is essentially the reverse of photosynthesis and is simplified as:

text:
In vertebrates, O
2 diffuses through membranes in the lungs and into red blood cells. Hemoglobin binds O
2, changing color from bluish red to bright red[35] (CO
2 is released from another part of hemoglobin through the Bohr effect). Other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters).[58] A liter of blood can dissolve 200 cm3 of O
2.[58]

text: Until the discovery of anaerobic metazoa,[69] oxygen was thought to be a requirement for all complex life.[70]

text:
Reactive oxygen species, such as superoxide ion (O−
2) and hydrogen peroxide (H
2O
2), are reactive by-products of oxygen use in organisms.[58] Parts of the immune system of higher organisms create peroxide, superoxide, and singlet oxygen to destroy invading microbes. Reactive oxygen species also play an important role in the hypersensitive response of plants against pathogen attack.[68] Oxygen is damaging to obligately anaerobic organisms, which were the dominant form of early life on Earth until O
2 began to accumulate in the atmosphere about 2.5 billion years ago during the Great Oxygenation Event, about a billion years after the first appearance of these organisms.[71][72]

text: An adult human at rest inhales 1.8 to 2.4 grams of oxygen per minute.[73] This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year.[g]

text: Living organisms

text:
Partial pressures of oxygen in the human body (PO2)

Unit
Alveolar pulmonary
gas pressures
Arterial blood oxygen
Venous blood gas

kPa
14.2
11[74]-13[74]
4.0[74]-5.3[74]

mmHg
107
75[75]-100[75]
30[76]-40[76]

text: The free oxygen partial pressure in the body of a living vertebrate organism is highest in the respiratory system, and decreases along any arterial system, peripheral tissues, and venous system, respectively. Partial pressure is the pressure that oxygen would have if it alone occupied the volume.[77]

text: Build-up in the atmosphere

text: Free oxygen gas was almost nonexistent in Earth's atmosphere before photosynthetic archaea and bacteria evolved, probably about 3.5 billion years ago. Free oxygen first appeared in significant quantities during the Paleoproterozoic eon (between 3.0 and 2.3 billion years ago).[78] For the first billion years, any free oxygen produced by these organisms combined with dissolved iron in the oceans to form banded iron formations. When such oxygen sinks became saturated, free oxygen began to outgas from the oceans 3–2.7 billion years ago, reaching 10% of its present level around 1.7 billion years ago.[78][79]

text:
The presence of large amounts of dissolved and free oxygen in the oceans and atmosphere may have driven most of the extant anaerobic organisms to extinction during the Great Oxygenation Event (oxygen catastrophe) about 2.4 billion years ago. Cellular respiration using O
2 enables aerobic organisms to produce much more ATP than anaerobic organisms.[80] Cellular respiration of O
2 occurs in all eukaryotes, including all complex multicellular organisms such as plants and animals.

text:
Since the beginning of the Cambrian period 540 million years ago, atmospheric O
2 levels have fluctuated between 15% and 30% by volume.[81] Towards the end of the Carboniferous period (about 300 million years ago) atmospheric O
2 levels reached a maximum of 35% by volume,[81] which may have contributed to the large size of insects and amphibians at this time.[82]

text: Variations in atmospheric oxygen concentration have shaped past climates. When oxygen declined, atmospheric density dropped, which in turn increased surface evaporation, causing precipitation increases and warmer temperatures.[83]

text:
At the current rate of photosynthesis it would take about 2,000 years to regenerate the entire O
2 in the present atmosphere.[84]

text: Industrial production

text:
One hundred million tonnes of O
2 are extracted from air for industrial uses annually by two primary methods.[12] The most common method is fractional distillation of liquefied air, with N
2 distilling as a vapor while O
2 is left as a liquid.[12]

text:
The other primary method of producing O
2 is passing a stream of clean, dry air through one bed of a pair of identical zeolite molecular sieves, which absorbs the nitrogen and delivers a gas stream that is 90% to 93% O
2.[12] Simultaneously, nitrogen gas is released from the other nitrogen-saturated zeolite bed, by reducing the chamber operating pressure and diverting part of the oxygen gas from the producer bed through it, in the reverse direction of flow. After a set cycle time the operation of the two beds is interchanged, thereby allowing for a continuous supply of gaseous oxygen to be pumped through a pipeline. This is known as pressure swing adsorption. Oxygen gas is increasingly obtained by these non-cryogenic technologies (see also the related vacuum swing adsorption).[85]

text:
Oxygen gas can also be produced through electrolysis of water into molecular oxygen and hydrogen. DC electricity must be used: if AC is used, the gases in each limb consist of hydrogen and oxygen in the explosive ratio 2:1. A similar method is the electrocatalytic O
2 evolution from oxides and oxoacids. Chemical catalysts can be used as well, such as in chemical oxygen generators or oxygen candles that are used as part of the life-support equipment on submarines, and are still part of standard equipment on commercial airliners in case of depressurization emergencies. Another air separation method is forcing air to dissolve through ceramic membranes based on zirconium dioxide by either high pressure or an electric current, to produce nearly pure O
2 gas.[61]

text: Storage

text: Oxygen storage methods include high pressure oxygen tanks, cryogenics and chemical compounds. For reasons of economy, oxygen is often transported in bulk as a liquid in specially insulated tankers, since one liter of liquefied oxygen is equivalent to 840 liters of gaseous oxygen at atmospheric pressure and 20 °C (68 °F).[12] Such tankers are used to refill bulk liquid oxygen storage containers, which stand outside hospitals and other institutions that need large volumes of pure oxygen gas. Liquid oxygen is passed through heat exchangers, which convert the cryogenic liquid into gas before it enters the building. Oxygen is also stored and shipped in smaller cylinders containing the compressed gas; a form that is useful in certain portable medical applications and oxy-fuel welding and cutting.[12]

text: Applications

text: Medical

text:
Uptake of O
2 from the air is the essential purpose of respiration, so oxygen supplementation is used in medicine. Treatment not only increases oxygen levels in the patient's blood, but has the secondary effect of decreasing resistance to blood flow in many types of diseased lungs, easing work load on the heart. Oxygen therapy is used to treat emphysema, pneumonia, some heart disorders (congestive heart failure), some disorders that cause increased pulmonary artery pressure, and any disease that impairs the body's ability to take up and use gaseous oxygen.[86]

text: Treatments are flexible enough to be used in hospitals, the patient's home, or increasingly by portable devices. Oxygen tents were once commonly used in oxygen supplementation, but have since been replaced mostly by the use of oxygen masks or nasal cannulas.[87]

text:
Hyperbaric (high-pressure) medicine uses special oxygen chambers to increase the partial pressure of O
2 around the patient and, when needed, the medical staff.[88] Carbon monoxide poisoning, gas gangrene, and decompression sickness (the 'bends') are sometimes addressed with this therapy.[89] Increased O
2 concentration in the lungs helps to displace carbon monoxide from the heme group of hemoglobin.[90][91] Oxygen gas is poisonous to the anaerobic bacteria that cause gas gangrene, so increasing its partial pressure helps kill them.[92][93] Decompression sickness occurs in divers who decompress too quickly after a dive, resulting in bubbles of inert gas, mostly nitrogen and helium, forming in the blood. Increasing the pressure of O
2 as soon as possible helps to redissolve the bubbles back into the blood so that these excess gasses can be exhaled naturally through the lungs.[86][94][95]

text: Life support and recreational use

text:
An application of O
2 as a low-pressure breathing gas is in modern space suits, which surround their occupant's body with the breathing gas. These devices use nearly pure oxygen at about one-third normal pressure, resulting in a normal blood partial pressure of O
2. This trade-off of higher oxygen concentration for lower pressure is needed to maintain suit flexibility.[96][97]

text:
Scuba and surface-supplied underwater divers and submariners also rely on artificially delivered O
2. Submarines, submersibles and atmospheric diving suits usually operate at normal atmospheric pressure. Breathing air is scrubbed of carbon dioxide by chemical extraction and oxygen is replaced to maintain a constant partial pressure. Ambient pressure divers breathe air or gas mixtures with an oxygen fraction suited to the operating depth. Pure or nearly pure O
2 use in diving at pressures higher than atmospheric is usually limited to rebreathers, or decompression at relatively shallow depths (~6 meters depth, or less),[98][99] or medical treatment in recompression chambers at pressures up to 2.8 bar, where acute oxygen toxicity can be managed without the risk of drowning. Deeper diving requires significant dilution of O
2 with other gases, such as nitrogen or helium, to prevent oxygen toxicity.[98]

text:
People who climb mountains or fly in non-pressurized fixed-wing aircraft sometimes have supplemental O
2 supplies.[h] Pressurized commercial airplanes have an emergency supply of O
2 automatically supplied to the passengers in case of cabin depressurization. Sudden cabin pressure loss activates chemical oxygen generators above each seat, causing oxygen masks to drop. Pulling on the masks "to start the flow of oxygen" as cabin safety instructions dictate, forces iron filings into the sodium chlorate inside the canister.[61] A steady stream of oxygen gas is then produced by the exothermic reaction.

text:
Oxygen, as a supposed mild euphoric, has a history of recreational use in oxygen bars and in sports. Oxygen bars are establishments found in Japan, California, and Las Vegas, Nevada since the late 1990s that offer higher than normal O
2 exposure for a fee.[100] Professional athletes, especially in American football, sometimes go off-field between plays to don oxygen masks to boost performance. The pharmacological effect is doubted; a placebo effect is a more likely explanation.[100] Available studies support a performance boost from oxygen enriched mixtures only if it is breathed during aerobic exercise.[101]

text: Other recreational uses that do not involve breathing include pyrotechnic applications, such as George Goble's five-second ignition of barbecue grills.[102]

text: Industrial

text:
Smelting of iron ore into steel consumes 55% of commercially produced oxygen.[61] In this process, O
2 is injected through a high-pressure lance into molten iron, which removes sulfur impurities and excess carbon as the respective oxides, SO
2 and CO
2. The reactions are exothermic, so the temperature increases to 1,700 °C.[61]

text:
Another 25% of commercially produced oxygen is used by the chemical industry.[61] Ethylene is reacted with O
2 to create ethylene oxide, which, in turn, is converted into ethylene glycol; the primary feeder material used to manufacture a host of products, including antifreeze and polyester polymers (the precursors of many plastics and fabrics).[61]

text:
Most of the remaining 20% of commercially produced oxygen is used in medical applications, metal cutting and welding, as an oxidizer in rocket fuel, and in water treatment.[61] Oxygen is used in oxyacetylene welding burning acetylene with O
2 to produce a very hot flame. In this process, metal up to 60 cm (24 in) thick is first heated with a small oxy-acetylene flame and then quickly cut by a large stream of O
2.[103]

text: Compounds

text: The oxidation state of oxygen is −2 in almost all known compounds of oxygen. The oxidation state −1 is found in a few compounds such as peroxides.[104] Compounds containing oxygen in other oxidation states are very uncommon: −1/2 (superoxides), −1/3 (ozonides), 0 (elemental, hypofluorous acid), +1/2 (dioxygenyl), +1 (dioxygen difluoride), and +2 (oxygen difluoride).[105]

text: Oxides and other inorganic compounds

text:
Water (H
2O) is an oxide of hydrogen and the most familiar oxygen compound. Hydrogen atoms are covalently bonded to oxygen in a water molecule but also have an additional attraction (about 23.3 kJ·mol−1 per hydrogen atom) to an adjacent oxygen atom in a separate molecule.[106] These hydrogen bonds between water molecules hold them approximately 15% closer than what would be expected in a simple liquid with just van der Waals forces.[107][i]

text:
Due to its electronegativity, oxygen forms chemical bonds with almost all other elements to give corresponding oxides. The surface of most metals, such as aluminium and titanium, are oxidized in the presence of air and become coated with a thin film of oxide that passivates the metal and slows further corrosion. Many oxides of the transition metals are non-stoichiometric compounds, with slightly less metal than the chemical formula would show. For example, the mineral FeO (wüstite) is written as Fe
1 − xO, where x is usually around 0.05.[108]

text:
Oxygen is present in the atmosphere in trace quantities in the form of carbon dioxide (CO
2). The Earth's crustal rock is composed in large part of oxides of silicon (silica SiO
2, as found in granite and quartz), aluminium (aluminium oxide Al
2O
3, in bauxite and corundum), iron (iron(III) oxide Fe
2O
3, in hematite and rust), and calcium carbonate (in limestone). The rest of the Earth's crust is also made of oxygen compounds, in particular various complex silicates (in silicate minerals). The Earth's mantle, of much larger mass than the crust, is largely composed of silicates of magnesium and iron.

text:
Water-soluble silicates in the form of Na
4SiO
4, Na
2SiO
3, and Na
2Si
2O
5 are used as detergents and adhesives.[109]

text:
Oxygen also acts as a ligand for transition metals, forming transition metal dioxygen complexes, which feature metal–O
2. This class of compounds includes the heme proteins hemoglobin and myoglobin.[110] An exotic and unusual reaction occurs with PtF
6, which oxidizes oxygen to give O2+PtF6−.[111]

text: Organic compounds

text:
Among the most important classes of organic compounds that contain oxygen are (where "R" is an organic group): alcohols (R-OH); ethers (R-O-R); ketones (R-CO-R); aldehydes (R-CO-H); carboxylic acids (R-COOH); esters (R-COO-R); acid anhydrides (R-CO-O-CO-R); and amides (R-C(O)-NR
2). There are many important organic solvents that contain oxygen, including: acetone, methanol, ethanol, isopropanol, furan, THF, diethyl ether, dioxane, ethyl acetate, DMF, DMSO, acetic acid, and formic acid. Acetone ((CH
3)
2CO) and phenol (C
6H
5OH) are used as feeder materials in the synthesis of many different substances. Other important organic compounds that contain oxygen are: glycerol, formaldehyde, glutaraldehyde, citric acid, acetic anhydride, and acetamide. Epoxides are ethers in which the oxygen atom is part of a ring of three atoms. The element is similarly found in almost all biomolecules that are important to (or generated by) life.

text:
Oxygen reacts spontaneously with many organic compounds at or below room temperature in a process called autoxidation.[112] Most of the organic compounds that contain oxygen are not made by direct action of O
2. Organic compounds important in industry and commerce that are made by direct oxidation of a precursor include ethylene oxide and peracetic acid.[109]

text: Safety and precautions

text: The NFPA 704 standard rates compressed oxygen gas as nonhazardous to health, nonflammable and nonreactive, but an oxidizer. Refrigerated liquid oxygen (LOX) is given a health hazard rating of 3 (for increased risk of hyperoxia from condensed vapors, and for hazards common to cryogenic liquids such as frostbite), and all other ratings are the same as the compressed gas form.[113]

text: Toxicity

text:
Oxygen gas (O
2) can be toxic at elevated partial pressures, leading to convulsions and other health problems.[98][j][115] Oxygen toxicity usually begins to occur at partial pressures more than 50 kilopascals (kPa), equal to about 50% oxygen composition at standard pressure or 2.5 times the normal sea-level O
2 partial pressure of about 21 kPa. This is not a problem except for patients on mechanical ventilators, since gas supplied through oxygen masks in medical applications is typically composed of only 30%–50% O
2 by volume (about 30 kPa at standard pressure).[7]

text:
At one time, premature babies were placed in incubators containing O
2-rich air, but this practice was discontinued after some babies were blinded by the oxygen content being too high.[7]

text:
Breathing pure O
2 in space applications, such as in some modern space suits, or in early spacecraft such as Apollo, causes no damage due to the low total pressures used.[96][116] In the case of spacesuits, the O
2 partial pressure in the breathing gas is, in general, about 30 kPa (1.4 times normal), and the resulting O
2 partial pressure in the astronaut's arterial blood is only marginally more than normal sea-level O
2 partial pressure.[117]

text:
Oxygen toxicity to the lungs and central nervous system can also occur in deep scuba diving and surface supplied diving.[7][98] Prolonged breathing of an air mixture with an O
2 partial pressure more than 60 kPa can eventually lead to permanent pulmonary fibrosis.[118] Exposure to a O
2 partial pressures greater than 160 kPa (about 1.6 atm) may lead to convulsions (normally fatal for divers). Acute oxygen toxicity (causing seizures, its most feared effect for divers) can occur by breathing an air mixture with 21% O
2 at 66 m (217 ft) or more of depth; the same thing can occur by breathing 100% O
2 at only 6 m (20 ft).[118][119][120][121]

text: Combustion and other hazards

text: Highly concentrated sources of oxygen promote rapid combustion. Fire and explosion hazards exist when concentrated oxidants and fuels are brought into close proximity; an ignition event, such as heat or a spark, is needed to trigger combustion.[27][122] Oxygen is the oxidant, not the fuel, but nevertheless the source of most of the chemical energy released in combustion.[27][34]

text:
Concentrated O
2 will allow combustion to proceed rapidly and energetically.[122] Steel pipes and storage vessels used to store and transmit both gaseous and liquid oxygen will act as a fuel; and therefore the design and manufacture of O
2 systems requires special training to ensure that ignition sources are minimized.[122] The fire that killed the Apollo 1 crew in a launch pad test spread so rapidly because the capsule was pressurized with pure O
2 but at slightly more than atmospheric pressure, instead of the 1⁄3 normal pressure that would be used in a mission.[k][124]

text: Liquid oxygen spills, if allowed to soak into organic matter, such as wood, petrochemicals, and asphalt can cause these materials to detonate unpredictably on subsequent mechanical impact.[122]


document_title: Early American currency

question_text: when was paper money first issued in the usa

text: Early American currency

text: Colonial currency[edit]

text: There were three general types of money in the colonies of British America: specie (coins), paper money and commodity money.[1] Commodity money was used when cash (coins and paper money) was scarce. Commodities such as tobacco, beaver skins, and wampum served as money at various times and places.[2]

text: Cash in the colonies was denominated in pounds, shillings, and pence.[2] The value varied from colony to colony; a Massachusetts pound, for example, was not equivalent to a Pennsylvania pound. All colonial pounds were of less value than the British pound sterling.[2] The coins in circulation in the colonies were most often of Spanish and Portuguese origin.[2] The prevalence of the Spanish dollar in the colonies led to the money of the United States being denominated in dollars rather than pounds.[2]

text: One by one, colonies began to issue their own paper money to serve as a convenient medium of exchange. In 1690, the Province of Massachusetts Bay created "the first authorized paper money issued by any government in the Western World."[3] This paper money was issued to pay for a military expedition during King William's War. Other colonies followed the example of Massachusetts Bay by issuing their own paper currency in subsequent military conflicts.[3]

text: The paper bills issued by the colonies were known as "bills of credit." Bills of credit were usually fiat money: they could not be exchanged for a fixed amount of gold or silver coins upon demand.[2][4] Bills of credit were usually issued by colonial governments to pay debts. The governments would then retire the currency by accepting the bills for payment of taxes. When colonial governments issued too many bills of credit or failed to tax them out of circulation, inflation resulted. This happened especially in New England and the southern colonies, which, unlike the Middle Colonies, were frequently at war.[4] Pennsylvania, however, was responsible in not issuing too much currency and it remains a prime example in history as a successful government-managed monetary system. Pennsylvania's paper currency, secured by land, was said to have generally maintained its value against gold from 1723 until the Revolution broke out in 1775.

text: This depreciation of colonial currency was harmful to creditors in Great Britain when colonists paid their debts with money that had lost value. The British Parliament passed several Currency Acts to regulate the paper money issued by the colonies. The Currency Act of 1751 restricted the emission of paper money in New England. It allowed the existing bills to be used as legal tender for public debts (i.e. paying taxes), but disallowed their use for private debts (e.g. for paying merchants).[5] In 1776, British (Scot) economist Adam Smith criticized colonial bills of credit in his most famous work, The Wealth of Nations.

text: Another Currency Act, in 1764, extended the restrictions to the colonies south of New England. Unlike the earlier act, this act did not prohibit the colonies in question from issuing paper money but it forbade them to designate their currency as legal tender for public or private debts. That prohibition created tension between the colonies and the mother country and has sometimes been seen as a contributing factor in the coming of the American Revolution. After much lobbying, Parliament amended the act in 1773, permitting the colonies to issue paper currency as legal tender for public debts.[6] Shortly thereafter, some colonies once again began issuing paper money. When the American Revolutionary War began in 1775, all of the rebel colonies, soon to be independent states, issued paper money to pay for military expenses.

text: Thirteen colony set of United States Colonial currency[edit]

text: The Thirteen Colony set of colonial currency below is from the National Numismatic Collection at the Smithsonian Institution. Examples were selected based on the notability of the signers, followed by issue date and condition. The initial selection criteria for notability was drawn from a list[7] of currency signers who were also known to have signed the United States Declaration of Independence, Articles of Confederation, the United States Constitution, or attended the Stamp Act Congress.[nb 1]

text:
Complete 13-colony set of United States Colonial currency[8][nb 2]

Colony
Value
Date
Issue
First[nb 3]
Note (obv)
Note (rev)
Signatures

Connecticut
40s
1775-01-02
£15,000[9]
1709[10]

Elisha Williams,
Thomas Seymour,
Benjamin Payne[nb 4]

Delaware
4s
1776-01-01
£30,000[12]
1723[13]

John McKinly,
Thomas Collins,
Boaz Manlove

Georgia
$40
1778-05-04
£150,000[nb 5]
1735[15]

Charles Kent,
William Few,
Thomas Netherclift,
William O’Bryen,[nb 6]
Nehemiah Wade

Maryland
$1
1770-03-01
$318,000[18]
1733[19]

John Clapham,
Robert Couden[nb 7]

Massachusetts
2s
1741-05-01
£50,000[21]
1690[22]

Robert Choate,
Jonathan Hale,
John Brown,
Edward Eveleth

New Hampshire
$1
1780-04-29
$145,000[23]
1709[10]

James McClure,
Ephraim Robinson,
Joseph Pearson,[nb 8]
John Taylor Gilman (rev)

New Jersey
12s
1776-03-25
£100,000[25]
1709[26]

Robert Smith,
John Hart,
John Stevens Jr.

New York
2s
1775-08-02
£2,500[27]
1709[28]

John Cruger Jr.,
William Waddell[nb 9]

North Carolina
£3
1729-11-27
£40,000[30]
1712[31]

William Downing,[nb 10]
John Lovick,[nb 11]
Edward Moseley,
Cullen Pollock,[nb 12]
Thomas Swann[nb 13]

Pennsylvania
20s
1771-03-20
£15,000[35]
1723[36]

Francis Hopkinson,
Robert Strettell Jones,
William Fisher[nb 14]

Rhode Island
$1
1780-07-02
£39,000[38]
1710[39]

Caleb Harris,
Metcalf Bowler,[nb 15]
Jonathan Arnold

South Carolina
$60
1779-02-08
$1,000,000[41]
1703[42]

John Scott,
John Smyth,
Plowden Weston[nb 16]

Virginia
£3
1773-03-04
£36,384[44]
1755[45]

Peyton Randolph,
John Blair Jr.,
Robert Carter Nicholas Sr.(rev)

text: Continental currency[edit]

text: After the American Revolutionary War began in 1775, the Continental Congress began issuing paper money known as Continental currency, or Continentals. Continental currency was denominated in dollars from $1⁄6 to $80, including many odd denominations in between. During the Revolution, Congress issued $241,552,780 in Continental currency.[46]

text: Continental currency depreciated badly during the war, giving rise to the famous phrase "not worth a continental".[47] A primary problem was that monetary policy was not coordinated between Congress and the states, which continued to issue bills of credit.[48] "Some think that the rebel bills depreciated because people lost confidence in them or because they were not backed by tangible assets," writes financial historian Robert E. Wright. "Not so. There were simply too many of them."[49] Congress and the states lacked the will or the means to retire the bills from circulation through taxation or the sale of bonds.[50]

text: Another problem was that the British successfully waged economic warfare by counterfeiting Continentals on a large scale. Benjamin Franklin later wrote:

text: The artists they employed performed so well that immense quantities of these counterfeits which issued from the British government in New York, were circulated among the inhabitants of all the states, before the fraud was detected. This operated significantly in depreciating the whole mass.[51]

text: By the end of 1778, Continentals retained from 1⁄5 to 1⁄7 of their face value. By 1780, the bills were worth 1⁄40 of their face value. Congress attempted to reform the currency by removing the old bills from circulation and issuing new ones, without success. By May 1781, Continentals had become so worthless that they ceased to circulate as money. Franklin noted that the depreciation of the currency had, in effect, acted as a tax to pay for the war.[52]

text: For this reason, some Quakers, whose pacifism did not permit them to pay war taxes, also refused to use Continentals, and at least one Yearly Meeting formally forbade its members to use the notes.[53] In the 1790s, after the ratification of the United States Constitution, Continentals could be exchanged for treasury bonds at 1% of face value.[54]

text: After the collapse of Continental currency, Congress appointed Robert Morris to be Superintendent of Finance of the United States. Morris advocated the creation of the first financial institution chartered by the United States, the Bank of North America, in 1782. The bank was funded in part by specie loaned to the United States by France. Morris helped finance the final stages of the war by issuing notes in his name, backed by his own money. The Bank of North America also issued notes convertible into specie.[55] Morris also presided over the creation of the first mint operated by the U.S. government, which struck the first coins of the United States, the Nova Constellatio patterns of 1783.[56]

text: The painful experience of the runaway inflation and collapse of the Continental dollar prompted the delegates to the Constitutional Convention to include the gold and silver clause into the United States Constitution so that the individual states could not issue bills of credit or "make any Thing but gold and silver Coin a Tender in Payment of Debts."[57] This restriction of bills of credit was extended to the Federal government, as the power to "emit bills" from the Articles of Confederation was abolished, leaving Congress with the power "to borrow money on credit.".[58][59]